Krell 900 - Manuals

A Letter from Dan D’Agostino Dear Audio Enthusiast, Thank you for your purchase of a Krell Evolution Series amplifier. Evolution Series amplifiers continue my quest for amplifiers that deliver absolute truth in music reproduction. Active Cascode Topology is a unique circuit technique that minimizes ...

6 SECTION ONE Evolution Amplifier Features and Technology This section describes the innovative features and technology of the Evolution Series amplifiers, and defines CAST and other key terms used in this reference. There are six amplifier models in the Evolution Series: the 302 Stereo Power Amplif...

7 Revolutionary Krell CAST Technology Current Audio Signal Transmission, termed CAST, is a revolutionary method of connecting analog audio components for unparalleled sonic performance. Innovative engineering combines the new Krell CAST circuitry with existing Krell Current Mode technology to create...

8 Krell Current Mode maintains the integrity of the signal within the component and CAST preserves the transmitted signal between components. Together, CAST and Krell Current Mode technologies unify separate Krell components into a single global circuit. Krell Current Mode technology enjoys bandwidt...

9 Definition of Terms The following are definitions of key terms used in this owner’s reference: Inputs and Outputs Balanced A symmetrical input or output circuit that has equal impedance from both input terminals to a common ground reference point. The industry standard for profes- sional and sound...

10 Technology Active Cascode Topology A unique circuit technique that minimizes distortion by applying from 2 to 3 times more active devices to each gain stage thereby reducing the load on individual devices and improving circuit-wide linearity. Krell Current Mode A proprietary Krell circuit topolog...

11 Unpacking and Placement This section describes the procedures for safely unpacking and placing your Evolution amplifier. The amplifier and accessories are shipped in 1 carton. The dimensions of the amplifier are shown in the specifications section starting on page 31. Two people are needed to rem...

12 Placement Before you install an Evolution amplifier into your system, please follow the guide- lines in this section to select a location for your component. This will facilitate a clean, trouble-free installation. Place the amplifier on a firm, level surface, away from excessive heat, humidity, ...

13 SECTION THREE Anatomy of an Evolution Amplifier This section describes Evolution amplifier functions. Figure 1 Evolution Amplifier Front Panel (Evolution 402 shown) 1 Power Button2 Power Status Indicator Power continued

14 Front Panel Description See Figure 1 on the previous page Evolution amplifier front panel functions are described below: Power 1 Power Button Press this button to place the Evolution amplifier in operational mode. 2 Power Status Indicator The power status indicator is illuminated in red when the ...

20 Back Panel Description See Figures 2, 3, 4, 5, and 6 on the previous pages The amplifier back panel provides access to the input and output connections, 12 V trigger inputs and outputs, and the AC power connection and switch. Back panel features and their descriptions follow: Outputs 3 Loudspeake...

21 Remote Connections 7 12 VDC In/Out (12 V Trigger) The 12 V trigger allows you to turn the Evolution amplifier on or to stand-by from other components. Out. The output sends 12 VDC (12 V trigger) power on/off signals to other Krell components and other devices that incorporate a 12 V trigger, allo...

22 SECTION FOUR Connecting an Evolution Amplifier to Your System This section describes Evolution amplifier connections. Each Evolution amplifier channel has a CAST 4-pin connector, a balanced input via an XLR connector, a single-ended RCA connector, and a pair of loudspeaker binding posts. The rear...

23 Evolution DC Protection Circuitry/Using Tube Preamplifiers The high DC output of tube preamplifiers may exceed the active DC protection circuitry of the Evolution amplifiers. Excessive DC level in a signal can damage amplifiers, loudspeakers, or both. The single-ended inputs of the Evolution ampl...

24 Evolution Amplifier Operation The Evolution amplifiers are easy to operate. IMPORTANT When powering up any system, turn the amplifier on last. When powering down, turn it off first. This will prevent any turn-on and turn-off thumps in your loudspeakers. Always mute or fully attenuate the preampli...

25 Troubleshooting System Noise AC grounding becomes critical when connecting high-performance audio compo- nents. When you mix and match high-performance audio components, each with its own ground potential, a low frequency hum may occur in one or both loud- speakers. This often occurs when introdu...

26 Error Codes In the event of a problem, the power status indicator (2) will flash error code(s) in red. Errors are identified by a sequence of 3, 4, or 5 flashes. There is a pause between codes, and in the case where there is only one error code, the same code is repeated. Diagnostic Code Possible...

27 Questions and Answers Q. Should I leave my Evolution amplifier on at all times? A. For maximum amplifier performance, leave the back panel power breaker switch on at all times. This places the amplifier in stand-by mode. Evolution amplifiers are designed to be powered on and off from stand-by, us...

28 Warranty Krell products have a limited warranty. Amplifiers, preamplifiers, preamp/processors,and receivers carry a limited warranty of five years for parts and labor on circuitry.Loudspeakers carry a limited warranty of five years for parts and labor. CD andDVD players carry a limited warranty o...

Return Authorization Procedure How to Expedite Service If you believe there is a problem with your component, please contact your deal- er, distributor, or the Krell factory to discuss the problem before you return the component for repair. To expedite service, you may wish to complete and e-mail th...

Specifications Measurement Evolution 302 Stereo Amplifier Evolution 402 Stereo Amplifier FREQUENCY RESPONSE 20 Hz to 20 kHz +0, –0.10 dB <0.5 Hz to 180 kHz +0, –3 dB 20 Hz to 20 kHz +0, –0.18 dB <0.5 Hz to 120 kHz +0, –3 dB SIGNAL-TO-NOISE RATIO Wideband, unweighted, referred to fullpower outp...